CSEG37SC Introduction to Seismic Inversion
Inversion involves extracting an estimate of the subsurface geology from a set of geophysical measurements. This course will focus on the inversion of seismic amplitude data to extract the velocities and densities of the reservoir, from which we can infer reservoir properties such as porosity and fluid content.
The earliest approach to inversion assumed that the seismic section is a frequency-limited set of reflection coefficients which can be recursively inverted to extract the impedance (the product of velocity and density) of the subsurface. Since most seismic data is recorded as compressional, or P-wave, data, this meant that the velocity component would be P-wave velocity. There are several limitations with this method. First, the low-frequency component is missing and must be estimated elsewhere. Second, P-wave velocity alone is not sufficient to estimate the fluid content of the reservoir.
To overcome the second problem, the AVO (Amplitude Versus Offset) method was developed in the 1980s, in which an estimate of the elastic properties of the earth could be obtained from the offset data (including S-wave information). This allowed us to estimate the fluid content of our reservoirs. Most recently, inversion and AVO have been combined to give a better estimate of the P-wave velocity, S-wave velocity and density. We can then estimate secondary parameters such as the porosity, sand content and water saturation using multivariate statistical approaches, which will also be discussed.
This course will stress the physical principles behind inversion and illustrate these methods with real data examples from the Western Canadian sedimentary basin and the Gulf of Mexico. The course will also discuss the practice of inversion and its limitations.
Course Outline
Part 1 Introduction
Part 2 Rock physics and fluid replacement modelling.
Part 3 Post-stack seismic inversion.
Part 4 AVO and pre-stack seismic inversion.
Part 5 Stochastic inversion
- - - - - - - - - - - - - - - - - -
Dr. Brian Russell holds a B.Sc. in Geophysics from the University of Saskatchewan, a M.Sc. in Geophysics from the Durham University, U.K., a Ph.D. in Geophysics from the University of Calgary. He started his career as a geophysicist with Chevron in 1975, and worked for Chevron affiliates in both Calgary and Houston. He then worked for Teknica and Veritas in Calgary before co-founding Hampson-Russell Software Ltd. in 1987 with Dan Hampson. Hampson-Russell develops and markets seismic inversion software which is used by oil and gas companies throughout the world. Since 2006, Hampson-Russell has been a fully owned subsidiary of CGGVeritas, where Brian is currently Vice President. Brian presents courses on advanced geophysical technology throughout the world and has given numerous technical papers at geophysical conferences. His papers have been published in Geophysics, The Leading Edge, Exploration Geophysics and The Journal of Petroleum Geology. His book Introduction to Seismic Inversion Methods was published by SEG in 1988.
Brian was President of the Canadian SEG (CSEG) in 1991, received the CSEG Meritorious Service Award in 1995, the CSEG medal in 1999, and CSEG Honorary Membership in 2001. He served as chairman of The Leading Edge editorial board in 1995, Technical Co-chairman of the Denver Annual Meeting in 1996, and as President of SEG in 1998. In 1996, Brian and Dan Hampson were awarded the SEG Enterprise Award; in 2005 he received SEG Life Membership and in 2008 was given Honorary Membership from SEG. Brian is registered as a Professional Geophysicist (P.Geoph.) in Alberta.
